https://bugs.winehq.org/show_bug.cgi?id=43474
--- Comment #3 from zaplo00@mailfence.com --- (In reply to Sebastian Lackner from comment #2)
Could you please test if the issue is also present with 2.14 (as soon as it is available in the repositories, or by compiling from source)? If this issue is related to backup window handling it was probably already fixed.
Window doesn't seem to unmap in 2.14 anymore and window isn't empty. Now it instead shows wallpaper from my first monitor inside the window and contents are not updated (dragging other window over it shows trailing window borders or other garbage). So problem still persists, just bit less annoying.